In the lay-up of glass block panels or walls, masons spread mortar on exposed edges of the blocks and set them in place. The spacing between the blocks, both vertically and horizontally, is generally "eye-balled" by the mason and determined by the amount of mortar spread on the edges and by tapping or lightly shifting the block when it is set in place. Such method of setting the blocks requires both a skilled mason and patient work to carefully adjust each block and is a time-consuming procedure.
As shown in the following patents, suggestions have been made to control the spacing between the blocks by the use of spacers which are disposed in the joints and hold the blocks in uniform spaced relation while the mortar sets: U.S. Pat. Nos. 4,114,337; 4,774,793. The spacers remain in place after the mortar sets. Because the spacers are consumed in the panel, not only must their cost be added to the panel cost, but their presence in the panel or wall renders it somewhat weaker then if only mortar was present. In addition, if the spacer remains in the wall, their pressure will prevent the wall from having an Underwritten Laboratory fire rating approval. In U.S. Pat. No. 4,408,398, a gauge member is shown which is removed from the mortar joint before the mortar sets up. However, such gauge will leave substantial holes in the mortar which are the diameter of the space between the blocks and would be difficult to fill.